Yes my Sencha Touch code uses the onReady feature, and focus does not work no matter where it gets initiated from, either a touch start or click event. Ounce you add the sencha js file focus will no longer work, no matter how you try to do it.
I just removed everything from my original sencha code and created a basic sample to illustrate that by just adding the js file it will break focus after button press on mobile safari. From my understanding mobile safari focus works as long as it's initiated from a touch even, like a button click.
Try the code above and by simple removing the sencha js file, the focus will work in mobile safari.
I did noticed that when using sencha and I tried to set focus, it will actually clear placeHolder text and looks like it was starting to do the focus but it never finishes.
Ok, so if I understand you correctly, you're only seeing this issue in Safari Mobile?
It works fine for me in OSX 10.6.8 in both Chrome and Safari, but obviously that's not the browser in which you're noting the problem. I'm not familiar enough with the specifics of that browser so I can't tell you if the issue is a bug or not.
I'm obviously not the person who needs to help you here. If you haven't done so already, please submit a ticket to support.sencha.com where the issue can be properly escalated. Once you've done that, I can try to apply some pressure to get you an answer.
Developer Relations Manager, Sencha Inc.